SERIALLY PROGRAMMABLE CLOCK SOURCE. Features

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Laurel Townsend
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1 DATASHEET ICS Description The ICS is a dynamic, serially programmable clock source which is flexible and takes up minimal board space. Output frequencies are programmed via a 3-wire SPI port. An advanced PLL coupled to an array of configurable output dividers and three outputs allows low-jitter generation of frequencies from 200 Hz to 270 MHz. The device can be reprogrammed during operation, making it ideal for applications where many different frequencies are required, or where the output frequency must be determined at run time. Glitch-free frequency transitions, where the clock period changes slightly over many cycles, are possible. Features Crystal or clock reference input 3.3 V CMOS outputs Three outputs can be individually configured or shut off Small 16-pin TSSOP package Pb-free, RoHS compliant Reprogrammable during operation 3-wire SPI serial interface Glitch-free output frequency switching User selectable charge pump current and damping resistor Power-down control via hardware pin or software control bit Programming word can be generated by IDT VersaClock II Software Directly programmable via VersaClock II Software and a Windows PC parallel port Industrial temperature range available Block Diagram (Table 1) Charge Pump (Table 3) Resistor (Table 4) X1 REF Divide CP 11pF 300 pf Divider CLK1 X2 [Bit 122] VCO DIVIDE (Table 5) [Bit 110] (Table 2) 1 0 Divider 2-34 CLK2 DIN CS SCLK Programming Register (132 bits) [Bit 123] (Table 6) [Bit 111] 1 0 Divider 2-34 CLK3 [Bit 124] [Bit 129] (Table 7) IDT 1 ICS REV L

2 Pin Assignment X X2 VDD 2 15 PD VDD 3 14 CLK3 VDD GND GND ICS GND CLK2 DIN GND 7 10 CS CLK1 8 9 SCLK 16-pin TSSOP Pin Descriptions Pin Number Pin Name Pin Type Pin Description 1 X1 XI Connect to input reference clock or crystal. 2 VDD Power Power connection for crystal oscillator. 3 VDD Power Power connection for PLL. 4 VDD Power Power connection for inputs and outputs. 5 GND Power Ground connection for crystal oscillator. 6 GND Power Ground connection for PLL. 7 GND Power Ground connection for inputs and outputs. 8 CLK1 Output Clock 1 output. 9 SCLK Input Programming interface - Serial clock input. Internal pull-up. 10 CS Input Programming interface - LOAD input. Internal pull-down. 11 DIN Input Programming interface - Serial data input. Internal pull-up. 12 CLK2 Output Clock 2 output. 13 GND Power Ground connection. 14 CLK3 Output Clock 3 output. 15 PD Input Crystal, PLL, and outputs are powered-down when low. Internal pull-up. 16 X2 - Connect to crystal. Leave open if reference clock input is used. IDT 2 ICS REV L

3 Table 1. Input Divider Divide Value Bits Rule 1 X X X X X X X X X X X Bit 0 2 X X X X X X X X X X X Bit 0 3 X X X X X X X subtract 2 from the 4 X X X X X X X desired value, convert to binary, invert, and apply 5 X X X X X X X to bits X X X X X X X Bits [1..0] = 10 7 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X subtract 8 from the desired divide value, convert to binary, and apply to bits Bits [1..0] = Table 2. VCO Divider Bits Divide Value Rule subtract 8 from the desired divide value, convert to binary, and apply to bits IDT 3 ICS REV L

4 Table 3. Charge Pump Current (I CP ) Bits Charge Pump Current (μa) Rule Icp = ([ ]+1)*1.25μA*([ ] + 1) Table 4. Loop Filter Resistor (R S ) Bits Resistor Value k k k k 1 1 IDT 4 ICS REV L

5 Table 5. Output Divider for Output 1 Divide Value Bits Rule 2 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X apply Rule from Divide Values X X X X X X X X X X X X X X X X X apply Rule from Divide Values X X X X X X X X X X X X X X X X X apply Rule from Divide Values X X X X X X X X X X X X X X X X X subtract 6 from the desired divide 15 X X X X X X X value, convert to binary, invert, and apply to bits set bits [97..95] = X X X X X X X X X X X X X X output divide = ((([ ]+3)*2)+[98])*2^[ ] set bits [95..97] = 101 (increments of 1) set bits [95..97] = ( this Rule applies to Divide Values ) (increments of 2) (increments of 4) (increments of 8) IDT 5 ICS REV L

6 Table 6. Output Divider for Output 2 Bits Divide Value Rule output divide = ([ ]+2)*2^[113]) Table 7. Output Divider for Output 3 Bits Divide Value Rule output divide = ([ ]+2)*2^[94]) IDT 6 ICS REV L

7 Table 8. Miscellaneous Control Bits Bit Function 24~88 Reserved set to OE1 set to 1 to enable CLK1 111 OE2 set to 1 to enable CLK = Normal Operation, 0 = power down feedback counter, charge pump and VCO 122 Crystal Input = 1, Clock Input = Selects source for CLK2 (see block diagram) 124 Selects source for CLK3 (see block diagram) 125 Reserved set to Reserved set to OE3 set to 1 to enable CLK3 130 Reserved set to Reserved set to 0 External Components The ICS requires a minimum number of external components for proper operation. Decoupling Capacitors TheICS requires 0.01μF decoupling capacitors to be connected between each VDD pin and the Ground Plane. The 0.01μF capacitors must be placed as close to the ICS s power pins as possible to minimize lead inductance. Output Termination The ICS has advanced output pads that allows the device to achieve very high speed (270 MHz) operation with single ended clock outputs. The clock outputs on the ICS are designed to be directly connected to a 50 Ohm transmission line without the need for any series resistors. Crystal Selection A parallel resonant, fundamental mode crystal with a load (correlation) capacitance of 12 pf should be used. For crystals with a specified load capacitance greater than 12 pf, additional crystal capacitors may be connected from each of the pins X1 and X2 to ground as shown in the Block Diagram on page 1. The value (in pf) of these crystal caps should be = (C L -12)*2, where C L is the crystal load capacitance in pf. For a single ended clock input, connect it to X1 and leave X2 unconnected with no capacitors on either pin. Initial Output Frequency ICS on-chip registers are initially configured to provide a 1x output clock on the CLK1 output, and 0.5x clock on CLK2 and CLK3. The output frequency will be the same as the input clock or crystal for input frequencies from MHz. This is useful when the ICS needs to provide an initial system clock at power-up. IDT 7 ICS REV L

8 Determining and Controlling the Output Frequency with VersaClock TM II The ICS is directly supported by the IDT provided software called VersaClock II. Complete programming words for this device can be calculated on any Windows PC by running the VersaClock II software and simple inputting desired input and output frequencies. Once the software generates an appropriate programming word, it may then be either copied to the Windows clipboard or even directly programmed into the ICS via the host computers parallel port. For more information on VersaClock II, please visit Manually Determining the Output Frequency The user has full control over the desired output frequency as long as it is operated within the limits shown in the AC Electrical Characteristics. The output of the ICS can be determined by the following equation: CLK1Frequency = InputFrequency V R OD Where: VCO Divider (V) = 12 to 2055 Reference Divider Word (R) = 1 to 2055 Output Divider = values in tables 5, 6, 7 Also, the following operating ranges should be observed. VCOmin < InputFrequency V --- < VCOmaxfreq R Input Frequency 20kHz < < 100MHz R To determine the best combination of VCO, reference, and output dividers, please use the VersaClock II software mentioned above. IDT 8 ICS REV L

9 Setting the PLL Loop Response The PLL loop response is determined both by fixed device characteristics and by other characterizes set by the user. This includes the values of R S and C S as shown in the PLL Components figure on this page. The PLL loop bandwidth is approximated by: NBW(PLL) R S I CP K O = π FV Divider Where: R S = Value of resistor R S in loop filter in Ohms I CP = Charge pump current in amps To prevent jitter due to modulation of the PLL by the phase detector frequency, the following general rule should be observed:. NBW(VCO PLL) The PLL loop damping factor is determined by: R S DF(VCLK) = f(phase Detector) I CP C S K O FV Divider Where: C S = Value of capacitor C S in loop filter in Farads = 300e -12 in Farads K O = VCO Gain in Hz/V FV Divider = 12 to 2055 The above equation calculates the normalized loop bandwidth (denoted as NBW ) which is approximately equal to the - 3dB bandwidth. NBW does not take into account the effects of damping factor or the second pole imposed by C P. It does, however, provide a useful approximation of filter performance. Default Register Values At power-up, the registers are set to: ref divide = 5 VCO divide = 50 output divide = 10 (CLK1) output divide = 2 (CLK2) output divide = 2 (CLK3) bit 123, 124 = 1 ICP = 3.75 µa R = 16k Default programming word is: 0x31FFDFFEE3BFFFFFFFFFFFFFFFF055FF2 IDT 9 ICS REV L

10 Programming Interface The dynamic register within the ICS controls the entire device and may be reprogrammed any time after power is properly applied. If V or R values are changed, the frequency will transition smoothly to the new value without glitches or short cycles. However, changing any divider or mux in the output signal path may generate a glitch. The register is 132 bits in length and accepts the MSB first. The SCLK signal latches the current data bit value in the rising edge. It latches the most recently shifted 132 bit values into the control register of device whenever CS is high. Care must be taken to ensure that CS is always low until the system is ready to load in a new register value and that SCLK is never toggled high when CS is high. The register can be programmed any time after power is applied, even while in power-down (pin 15 or bit 112 held low) with the waveform and timing shown below:. Figure 2: ICS Programming Timing Diagram DIN t setup t hold SCLK t w t s CS Table 8: AC Parameters for Programming the ICS Parameter Condition Min. Max. Units t SETUP Setup time 2.5 ns t HOLD Hold time after SCLK 2.5 ns t W Data wait time 2.5 ns t S Strobe pulse width 10 ns SCLK Frequency 200 MHz Programming with VersaClock Software The VersaClock II Software not only generates the programming word for the user, it can also be used to program the device via the host computer s parallel port. Demonstration boards are available from IDT that allows the VersaClock II S/W to directly connect the ICS to a Windows based PC s DB-25 parallel port connector and programmed simply by pressing the Program Part button. IDT 10 ICS REV L

11 Absolute Maximum Ratings Stresses above the ratings listed below can cause permanent damage to the ICS These ratings, which are standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical parameters are guaranteed only over the recommended operating temperature range. Supply Voltage, VDD All Inputs and Outputs Storage Temperature Soldering Temperature Item Rating 5 V -0.5 V to VDD+0.5 V -65 to +150 C 260 C Recommended Operating Conditions Parameter Min. Typ. Max. Units Ambient Operating Temperature C Power Supply Voltage (measured in respect to GND) V DC Electrical Characteristics VDD=3.3 V ±0.3 V, Ambient temperature 0 to +70 C, unless stated otherwise Parameter Symbol Conditions Min. Typ. Max. Units Operating Voltage VDD V Input High Voltage V IH 2 V Input Low Voltage V IL 0.8 V Output High Voltage V OH I OH = -4 ma 2.4 V Output Low Voltage V OL I OL = 4 ma 0.4 V Output High Voltage, V OH I OH = -6.5 ma VDD-0.4 V CMOS level Tri-state Output Leakage 1 µa Operating Supply Current IDD 27 MHz crystal No load, 100 MHz out, all outputs enabled 24 ma Short Circuit Current CLK outputs ±60 ma Input Capacitance C IN 4 pf On-Chip Pull-up Resistor R PU 240 kω On-Chip Pull-down Resistor R PD 100 kω IDT 11 ICS REV L

12 AC Electrical Characteristics VDD = 3.3 V ±0.3 V, Ambient Temperature 0 to +70 C, unless stated otherwise Parameter Symbol Conditions Min. Typ. Max. Units Input Frequency F IN Fundamental crystal 3 27 MHz Clock MHz Clock Output Frequency F OUT 5 pf load MHz 15 pf load MHz Output Clock Rise/Fall Time t R, t F 20 to 80% (5 pf load) 1.5 ns Output Clock Duty Cycle Output Divides <> % Output Divide = % Frequency Transition time STROBE high to CLK 3 10 ms out One Sigma Clock Period Jitter Note 2 50 ps Maximum Absolute Jitter t ja Deviation from mean, Note 2 ±120 ps VCO Frequency VCO F MHz Divider 1 Input Output divider 1 = MHz (5 pf load) Output divider 1 = MHz (15 pf load) Output divider 1 = MHz (5 pf load) Output divider 1 = MHz (15 pf load) Output divider 1 = MHz ~ 1029 All other Output 730 MHz Divider 1 values Divider 2 and 3 Inputs Output divider 2, 3 = MHz (5 pf load) Output divider 2, 3 = MHz (15 pf load) Output divider 2, 3= MHz Output divider 2, 3 = 500 MHz 16, 24, 28 and 32 All other Output Divider 2 & 3 values 730 MHz Note 1: Measured with 15 pf load. Note 2: Jitter performance will change depending on configuration settings. IDT 12 ICS REV L

13 Package Outline and Package Dimensions (16-pin TSSOP, 4.40 mm Body, 0.65 mm Pitch) Package dimensions are kept current with JEDEC Publication No. 95, MO Millimeters Inches* INDEX AREA 1 2 D E1 E Symbol Min Max Min Max A A A b C D E 6.40 BASIC BASIC E e 0.65 Basic Basic L α aaa A 2 A *For reference only. Controlling dimensions in mm. A 1 - C - c e b aaa SEATING PLANE C L Ordering Information Part / Order Number Marking Shipping packaging Package Temperature 307G-03LF 307G03LF Tubes 16-pin TSSOP 0 to +70 C 307G-03LFT 307G03LF Tape and Reel 16-pin TSSOP 0 to +70 C 307GI-03LF 307GI03L Tubes 16-pin TSSOP -40 to +85 C 307GI-03LFT 307GI03L Tape and Reel 16-pin TSSOP -40 to +85 C "LF" suffix to the part number denotes Pb-Free configuration, RoHS compliant. While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (IDT) assumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing by IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT does not authorize or warrant any IDT product for use in life support devices or critical medical instruments. IDT 13 ICS REV L

Innovate with IDT and accelerate your future networks. Contact: www.idt.com For Sales 800-345-7015 408-284-8200 Fax: 408-284-2775 For Tech Support www.idt.com/go/clockhelp Corporate Headquarters Integrated Device Technology, Inc.

14 Innovate with IDT and accelerate your future networks. Contact: For Sales Fax: For Tech Support Corporate Headquarters Integrated Device Technology, Inc Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT and the IDT logo are trademarks of Integrated Device Technology, Inc. Accelerated Thinking is a service mark of Integrated Device Technology, Inc. All other brands, product names and marks are or may be trademarks or registered trademarks used to identify products or services of their respective owners. Printed in USA

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